Increased plasma apoM levels in the patients suffered from hepatocellular carcinoma and other chronic liver diseases

The role of novel adipokines in hepatocellular carcinoma progression: a mini review

Hepatocellular carcinoma (HCC), which originates from hepatocytes, accounts for the majority of primary liver cancers. Globally, HCC ranks among the most common cancers and is a leading cause of cancer-related deaths. Obesity, a growing health issue worldwide, is increasingly recognized as a critical risk factor for HCC, influenced by both epidemiological and clinical factors. Adipokines, secreted by adipocytes, have been shown to play pivotal roles in the tumor microenvironment, affecting cancer progression, metastasis, and resistance to therapies through various signaling mechanisms. Despite inconsistencies in certain findings, a substantial body of research supports the significant role of adipokines in HCC development. This review focuses on exploring newly identified adipokines and their mechanisms in HCC, with the goal of uncovering potential therapeutic targets for improved management and treatment strategies.

A rapid quantitative UPLC-MS/MS method for analysis of key regulatory oxysterols in biological samples for liver cancer

An UPLC-APCI-MS/MS method was developed for the simultaneous determination of cholesterol, 7-dehydrocholesterol (7DHC) and eight oxysterols including 27-hydroxycholesterol (27OHC), 7α-hydroxycholesterol (7αOHC), 7β-hydroxycholesterol (7βOHC), 24S-hydroxycholesterol (24SOHC), 25-hydroxycholesterol (25OHC), 7α,24S-dihydroxycholesterol (7α,24SdiOHC), 7α,25-dihydroxycholesterol (7α,25diOHC), and 7α,27-dihydroxycholesterol (7α,27diOHC). It has been used for quantitative analysis of cholesterol, 7DHC and eight oxysterols in hepatocellular carcinoma (HCC) cells, plasma and tumor tissue samples. And the above compounds were extracted from the biological matrix (plasma and tissue) using liquid-liquid extraction with hexane/isopropanol after saponification to cleave the steroids from their esterified forms without further derivatization. Then cholesterol, 7DHC and oxysterols were separated on a reversed phase column (Agilent Zorbax Eclipse plus, C18) within 8 min using a gradient elution with 0.1 % formic acid in H2O and methanol and detected by an APCI triple quadrupole mass spectrometer. The lower limit of quantification (LLOQ) of the cholesterol, 7DHC and oxysterols ranged from 3.9 ng/mL to 31.25 ng/mL, and the recoveries ranged from 83.0 % to 113.9 %. Cholesterol, 7DHC and several oxysterols including 27OHC, 7αOHC and 7βOHC were successfully quantified in HCC cells, plasma, tissues and urine of HCC mice. Results showed that 27OHC was at high levels in three kind of HCC cells and tumor tissues as well as plasma samples from both HepG2 and Huh7 bearing mice model，and the high levels of 27OHC in tumors were associated with HCC development. Moreover, the levels of cholesterol in HCC cells and tumor issues varied in different HCC cells and mice model. Oxysterols profiling in biological samples might provide complementary information in cancer diagnosis.

All we need to know about lipoprotein(a)

Lipoprotein(a) [Lp(a)], a genetically determined macromolecular complex, is independently and causally associated with atherosclerotic cardiovascular disease (ASCVD) and calcific aortic stenosis via proposed proinflammatory, prothrombotic, and proatherogenic mechanisms. While Lp(a) measurement standardization issues are being resolved, several guidelines now support testing Lp(a) at least once in each adult's lifetime for ASCVD risk prediction which can foster implementation of more aggressive primary or secondary prevention therapies. Currently, there are several emerging targeted Lp(a) lowering therapies in active clinical investigation for safety and cardiovascular benefit among both primary and secondary prevention populations. First degree relatives of patients with high Lp(a) should be encouraged to undergo cascade screening. Primary prevention patients with high Lp(a) should consider obtaining a coronary calcium score for further risk estimation and to guide further ASCVD risk factor management including consideration of low dose aspirin therapy. Secondary prevention patients with high Lp(a) levels should consider adding PCSK9 inhibition to statin therapy.

The Ability of Lipoprotein (a) Level to Predict Early Carotid Atherosclerosis Is Impaired in Patients With Advanced Liver Fibrosis Related to Metabolic-Associated Fatty Liver Disease

INTRODUCTION

Hepatic fibrosis reduces the serum level of lipoprotein (a) (Lp(a)) and may affect its accuracy in cardiovascular disease prediction of metabolic-associated fatty liver disease (MAFLD). We aimed to estimate the association between Lp(a) levels and the risk of carotid atherosclerosis in MAFLD patients with advanced fibrosis.

METHODS

This was a cross-sectional study enrolling 4,348 consecutive individuals (1,346 patients with MAFLD and 3,002 non-MAFLD patients) who were admitted to the First Affiliated Hospital, Sun Yat-sen University, and underwent abdominal and carotid ultrasonography from 2015 to 2021. Lp(a) levels, liver biochemical markers, metabolic indices, and anthropometric parameters were measured. Liver fat content and fibrosis severity were assessed by MRI-PDFF, using the NAFLD fibrosis score (NFS) and liver stiffness measurement (LSM) of two-dimensional shear wave elastography, respectively.

RESULTS

There was an L-shaped relationship between Lp(a) levels and LSMs in patients with MAFLD, and Lp(a) levels had a different relationship with liver fat content in MAFLD patients with F1-2 versus those with F3-4. Non-MAFLD patients had higher levels of Lp(a) than MAFLD patients with or without advanced fibrosis (both P < 0.05). Lp(a) levels and degree of liver fibrosis were both positively correlated with carotid atherosclerosis in patients with MAFLD. Lp(a) levels performed well on carotid atherosclerosis risk prediction for non-MAFLD patients with an area under the curve (AUC) of 0.819, which was significantly better than the carotid atherosclerosis risk prediction for MAFLD patients with NFS ≤ -1.836 (AUC: 0.781), NFS > -1.836 (AUC: 0.692), and LSM ≥ 9.0 kPa (AUC: 0.635) (all P < 0.05).

DISCUSSION

Advanced liver fibrosis significantly reduces the predictive value of Lp(a) levels for the risk of carotid atherosclerosis in patients with MAFLD.

Non-genetic influences on lipoprotein(a) concentrations

An elevated level of lipoprotein(a) [Lp(a)] is a genetically regulated, independent, causal risk factor for cardiovascular disease. However, the extensive variability in Lp(a) levels between individuals and population groups cannot be fully explained by genetic factors, emphasizing a potential role for non-genetic factors. In this review, we provide an overview of current evidence on non-genetic factors influencing Lp(a) levels with a particular focus on diet, physical activity, hormones and certain pathological conditions. Findings from randomized controlled clinical trials show that diets lower in saturated fats modestly influence Lp(a) levels and often in the opposing direction to LDL cholesterol. Results from studies on physical activity/exercise have been inconsistent, ranging from no to minimal or moderate change in Lp(a) levels, potentially modulated by age and the type, intensity, and duration of exercise modality. Hormone replacement therapy (HRT) in postmenopausal women lowers Lp(a) levels with oral being more effective than transdermal estradiol; the type of HRT, dose of estrogen and addition of progestogen do not modify the Lp(a)-lowering effect of HRT. Kidney diseases result in marked elevations in Lp(a) levels, albeit dependent on disease stages, dialysis modalities and apolipoprotein(a) phenotypes. In contrast, Lp(a) levels are reduced in liver diseases in parallel with the disease progression, although population studies have yielded conflicting results on the associations between Lp(a) levels and nonalcoholic fatty liver disease. Overall, current evidence supports a role for diet, hormones and related conditions, and liver and kidney diseases in modifying Lp(a) levels.

Serum Glycoprotein Markers in Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma

Fatty liver disease progresses through stages of fat accumulation and inflammation to nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis, and eventually hepatocellular carcinoma (HCC). Currently available diagnostic tools for HCC lack sensitivity and specificity. In this study, we investigated the use of circulating serum glycoproteins to identify a panel of potential prognostic markers that may be indicative of progression from the healthy state to NASH and further to HCC. Serum samples were processed and analyzed using a novel high-throughput glycoproteomics platform. Our initial dataset contained healthy, NASH, and HCC serum samples. We analyzed 413 glycopeptides, representing 57 abundant serum proteins, and compared among the three phenotypes. We studied the normalized abundance of common glycoforms and found 40 glycopeptides with statistically significant differences in abundances in NASH and HCC compared to controls. Summary level relative abundances of core-fucosylated, sialylated, and branched glycans containing glycopeptides were higher in NASH and HCC as compared to controls. We replicated some of our findings in an independent set of samples of individuals with benign liver conditions and HCC. Our results may be of value in the management of liver diseases. Data generated in this work can be downloaded from MassIVE (https://massive.ucsd.edu) with identifier MSV000088809.

Genetics of Lipoprotein(a): Cardiovascular Disease and Future Therapy

PURPOSE OF REVIEW

Lipoprotein(a) levels are determined 80-90% by genetics and differ by up to 1000-fold between individuals. This review discusses the most recent literature on lipoprotein(a) as a risk factor for cardiovascular disease, as well as future lipoprotein(a)lowering therapies.

RECENT FINDINGS

Over the past few decades, numerous studies have observed that high lipoprotein(a) levels are associated observationally and causally through human genetics with increased risk of cardiovascular disease. Also, the development of safe and effective therapies to lower lipoprotein(a) is ongoing, most importantly using antisense oligonucleotides to prevent production of lipoprotein(a). Finally, both observational and genetic studies have estimated the extent to which lowering of lipoprotein(a) is needed to obtain a clinically meaningful reduction in the risk of cardiovascular disease. Lipoprotein(a) is a causal risk factor for cardiovascular disease; however, currently no approved safe and effective therapy is available to lower lipoprotein(a) levels. That said, promising randomized studies using antisense oligonucleotides show up to 80% reductions in lipoprotein(a), reductions that hopefully will result in lowering the risk of cardiovascular disease as presently tested in the ongoing HORIZON phase 3 trial.

The apoM-S1P axis in hepatic diseases

Liver dysfunction is always accompanied by lipid metabolism dysfunction. Apolipoprotein M (apoM), a member of the apolipoprotein family, is primarily expressed and secreted from the liver. apoM is the main chaperone of sphingosine-1-phosphate (S1P), a small signalling molecule associated with numerous physiologic and pathophysiologic processes. In addition to transport, apoM also influences the biologic effects of S1P. Most recently, numerous studies have investigated the potential role of the apoM-S1P axis in a variety of hepatic diseases. These include liver fibrosis, viral hepatitis B and C infection, hepatobiliary disease, non-alcoholic and alcoholic steatohepatitis, acute liver injury and hepatocellular carcinoma. In this review, the roles of apoM and S1P in the development of hepatic diseases are summarized, and novel insights into the diagnosis and treatment of hepatic diseases are discussed.

Comprehensive lipidomics in apoM-/- mice reveals an overall state of metabolic distress and attenuated hepatic lipid secretion into the circulation

Apolipoprotein M (apoM) participates in both high-density lipoprotein and cholesterol metabolism. Little is known about how apoM affects lipid composition of the liver and serum. In this study, we systemically investigated the effects of apoM on liver and plasma lipidomes and how apoM participates in lipid cycling, via apoM knockout in mice and the human SMMC-7721 cell line. We used integrated mass spectrometry-based lipidomics approaches to semiquantify more than 600 lipid species from various lipid classes, which include free fatty acids, glycerolipids, phospholipids, sphingolipids, glycosphingolipids, cholesterol, and cholesteryl esters (CEs), in apoM^-/- mouse. Hepatic accumulation of neutral lipids, including CEs, triacylglycerols, and diacylglycerols, was observed in apoM^-/- mice; while serum lipidomic analyses showed that, in contrast to the liver, the overall levels of CEs and saturated/monounsaturated fatty acids were markedly diminished. Furthermore, the level of ApoB-100 was dramatically increased in the liver, whereas significant reductions in both ApoB-100 and low-density lipoprotein (LDL) cholesterol were observed in the serum of apoM^-/- mice, which indicated attenuated hepatic LDL secretion into the circulation. Lipid profiles and proinflammatory cytokine levels indicated that apoM^-/- leads to hepatic steatosis and an overall state of metabolic distress. Taken together, these results revealed that apoM knockout leads to hepatic steatosis, impaired lipid secretion, and an overall state of metabolic distress.

Apolipoprotein: prospective biomarkers in digestive tract cancer

Digestive tract cancer, which is characterized by high morbidity and mortality, seriously affects the quality of life of patients worldwide. The digestive tract has abundant blood supply and nutriment, providing a suitable environment for tumor cells. Under chemical, physical, and biological stimuli, the activated cancer-related genes promote tumorigenesis. The synthesis of apolipoprotein occurs in the liver, intestine, and other digestive organs. However, the functions of apolipoproteins are not limited to lipid metabolism. An increasing number of studies have revealed that apolipoproteins take part in the regulation of tumor behavior. Apolipoprotein A (apoA) has recently been acknowledged as a beneficial indicator of several cancers, including colon, hepatocellular, and pancreatic cancer. Apolipoprotein E (apoE) can affect tumor susceptibility on account of genetic polymorphism. Levels of apolipoprotein C (apoC), B (apoB), and D (apoD) also impact tumor progression and the prognosis of patients. However, because of individual, racial, and genetic differences, a consensus has not yet been reached. Based on clinical data and analysis, apolipoproteins could be a novel target and marker in tumor therapy and prevention.

Advanced fibrosis of non-alcoholic steatohepatitis affects the significance of lipoprotein(a) as a cardiovascular risk factor

BACKGROUND AND AIMS

Lipoprotein(a) [Lp(a)] is an important independent cardiovascular risk factor. However, Lp(a) levels are lower in patients with chronic liver disease than in healthy subjects. Furthermore, Lp(a) levels decrease as residual liver function declines. Although non-alcoholic fatty liver disease (NAFLD), especially advanced non-alcoholic steatohepatitis (NASH), increases the risk of cardiovascular diseases, the relationship between serum Lp(a) level and NASH is unknown. Thus, we examined the relationship between serum Lp(a) levels and biopsy-proved NAFLD and clarified the significance of Lp(a) measurements for cardiovascular disease screening in patients with NAFLD.

METHODS

A total of 176 patients with NAFLD were enrolled. Comprehensive blood chemistry tests and histological examinations of liver samples were conducted. The relationship between serum Lp(a) levels and NAFLD was analyzed.

RESULTS

Serum Lp(a) levels in advanced fibrosis (stage 3-4) were lower than those in non-advanced fibrosis (stage 0-2) (p < 0.05). After adjustment for age, sex, body mass index, alanine aminotransferase (ALT), creatinine (Cre), HbA_1c level, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and the use of lipid-lowering agents, the significant inverse association between advanced fibrosis and serum Lp(a) levels remained (p < 0.01). Although the Lp(a) level was inversely associated with an NAFLD Activity Score (NAS) of 5-8, there was no significant association between Lp(a) levels and NAS adjusted for age, sex, body mass index, ALT, Cre, HbA_1c level, HDL-C, LDL-C, TG, and the use of lipid-lowering agents.

CONCLUSIONS

Advanced NASH is associated with low serum Lp(a) levels; therefore, Lp(a) levels may not be useful in evaluating cardiovascular risk.

Maternal Consumption of a Low-Isoflavone Soy Protein Isolate Diet Accelerates Chemically Induced Hepatic Carcinogenesis in Male Rat Offspring

It has been reported that maternal nutrition determines the offspring's susceptibility to chronic diseases including cancer. Here, we investigated the effects of maternal diets differing in protein source on diethylnitrosamine (DEN)-induced hepatocarcinogenesis in adult rat offspring. Dams were fed a casein (CAS) diet or a low-isoflavone soy protein isolate (SPI) diet for two weeks before mating and throughout pregnancy and lactation. Offspring were weaned to and fed a chow diet throughout the study. From four weeks of age, hepatocellular carcinomas (HCC) were induced by intraperitoneal injection of DEN once a week for 14 weeks. The SPI/DEN group exhibited higher mortality rate, tumor multiplicity, and HCC incidence compared with the CAS/DEN group. Accordingly, altered cholesterol metabolism and increases in liver damage and angiogenesis were observed in the SPI/DEN group. The SPI/DEN group had a significant induction of the nuclear factor-κB-mediated anti-apoptotic pathway, as measured by increased phosphorylation of IκB kinase β, which may lead to the survival of precancerous hepatocytes. In conclusion, maternal consumption of a low-isoflavone soy protein isolate diet accelerated chemically induced hepatocarcinogenesis in male rat offspring in the present study, suggesting that maternal dietary protein source may be involved in DEN-induced hepatocarcinogenesis in adult offspring.

Thrombophilia in hepatocellular carcinoma

Background

Chronic liver disease and hepatocellular carcinoma (HCC) can cause a disturbance in the coagulation system. In this study, we aimed to assess the risk factors for venous thromboembolism either acquired or hereditary in patients with HCC.

Results

Serum levels of proteins C and S, AT activity, and lipoprotein (a) were significantly lower in both HCC and cirrhotic patients while homocysteine levels were significantly higher in HCC patients. The prevalence of activated protein C resistance (APCR) and factor V Leiden (FVL) mutation was higher in HCC patients but with no significant differences between the studied groups. With multivariate analysis, prothrombin time, Fbg, protein C and S deficiency, increased lipoprotein (a), hyperhomocysteinemia, APCR, and FVL mutation were independent risk factors for thromboembolic complications in HCC patients.

Conclusions

Thrombophilic abnormalities are prevalent in HCC patients, and they have a substantial increased risk of venous thromboembolism.

Decreased expression of ApoF associates with poor prognosis in human hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is frequently associated with metabolism dysfunction. Increasing evidence has demonstrated the crucial role of lipid metabolism in HCC progression. The function of apolipoprotein F (ApoF), a lipid transfer inhibitor protein, in HCC is incompletely understood. We aimed to evaluate the functional role of ApoF in HCC in this study.

Methods

We used quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to detect ApoF mRNA expression in HCC tissues and hepatoma cell lines (SMMC-7721, HepG2, and Huh7). Immunohistochemistry was performed to detect the expression of ApoF in HCC tissues. The associations between ApoF expression and clinicopathological features as well as HCC prognosis were analyzed. The effect of ApoF on cellular proliferation and growth of SMMC-7721 and Huh7 cells was examined in vitro and in vivo.

Results

ApoF expression was significantly down-regulated at both mRNA and protein levels in HCC tissues as compared with adjacent tissues. In SMMC-7721 and Huh7 HCC cells, ApoF overexpression inhibited cell proliferation and migration. In a xenograft nude mouse model, ApoF overexpression effectively controlled HCC growth. Kaplan–Meier analysis results showed that the recurrence-free survival rate of HCC patients with low ApoF expression was significantly lower than that of other HCC patients. Low ApoF expression was associated with several clinicopathological features such as liver cirrhosis, Barcelona Clinic Liver Cancer stage and tumor-node-metastasis stage.

Conclusions

ApoF expression was down-regulated in HCC, which was associated with low recurrence-free survival rate. ApoF may serve as a tumor suppressor in HCC and be a potential application for the treatment of this disease.

Serum proteome mapping of EGF transgenic mice reveal mechanistic biomarkers of lung cancer precursor lesions with clinical significance for human adenocarcinomas

Atypical adenomatous hyperplasia (AAH) of the lung is a pre-invasive lesion (PL) with high risk of progression to lung cancer (LC). However, the pathways involved are uncertain. We searched for novel mechanistic biomarkers of AAH in an EGF transgenic disease model of lung cancer. Disease regulated proteins were validated by Western immunoblotting and immunohistochemistry (IHC) of control and morphologically altered respiratory epithelium. Translational work involved clinical resection material. Collectively, 68 unique serum proteins were identified by 2DE-MALDI-TOF mass spectrometry and 13 reached statistical significance (p < 0.05). EGF, amphiregulin and the EGFR endosomal sorting protein VPS28 were induced up to 5-fold while IHC confirmed strong induction of these proteins. Furthermore, ApoA1, α-2-macroglobulin, and vitamin-D binding protein were nearly 6- and 2-fold upregulated in AAH; however, ApoA1 was oppositely regulated in LC to evidence disease stage dependent regulation of this tumour suppressor. Conversely, plasminogen and transthyretin were highly significantly repressed by 3- and 20-fold. IHC confirmed induced ApoA1, Fetuin-B and transthyretin expression to influence calcification, inflammation and tumour-infiltrating macrophages. Moreover, serum ApoA4, ApoH and ApoM were 2-, 2- and 6-fold repressed; however tissue ApoM and sphingosine-1-phosphate receptor expression was markedly induced to suggest a critical role of sphingosine-1-phosphate signalling in PL and malignant transformation. Finally, a comparison of three different LC models revealed common and unique serum biomarkers mechanistically linked to EGFR, cMyc and cRaf signalling. Their validation by IHC on clinical resection material established relevance for distinct human lung pathologies. In conclusion, we identified mechanistic biomarker candidates recommended for in-depth clinical evaluation.

Lysophospholipids in laboratory medicine

Lysophospholipids (LPLs), such as lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and lysophosphatidylserine (LysoPS), are attracting attention as second-generation lipid mediators. In our laboratory, the functional roles of these lipid mediators and the mechanisms by which the levels of these mediators are regulated in vivo have been studied. Based on these studies, the clinical introduction of assays for LPLs and related proteins has been pursued and will be described in this review. Although assays of these lipids themselves are possible, autotaxin (ATX), apolipoprotein M (ApoM), and phosphatidylserine-specific phospholipase A₁ (PS-PLA₁) are more promising as alternate biomarkers for LPA, S1P, and LysoPS, respectively. Presently, ATX, which produces LPA through its lysophospholipase D activity, has been shown to be a useful laboratory test for the diagnosis and staging of liver fibrosis, whereas PS-PLA₁ and ApoM are considered to be promising clinical markers reflecting the in vivo actions induced by LysoPS and S1P.

Positive association between serum apolipoprotein M levels and hepatitis B virus DNA load in HBeAg-negative chronic hepatitis B

BACKGROUND

Hepatitis virus B (HBV) has infected millions of people worldwide. Notably, such infections can be associated with hepatic complications. Levels of apolipoprotein M (apoM), a component of high-density lipoprotein (HDL), are known to be significantly elevated in patients with chronic hepatitis B (CHB). The aim of this study was to investigate the relationship between HBV DNA load in serum and serum apoM levels in patients with CHB.

METHODS

A total of 73 HBeAg-negative CHB patients, 50 HBeAg-positive CHB patients, and 79 non-CHB controls were included in the study cohort. The age and body mass index (BMI) of the study participants were matched. Serum levels of apoM and the HBV antigens HBsAg and HBeAg were measured by enzyme-linked immunosorbent assay (ELISA) analysis. Serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), cholesterol, and triglycerides (TG) were assessed using an automatic biochemical analyzer. Serum HBV DNA levels were quantified by real-time PCR analysis. Data were analyzed by Spearman's rank correlation coefficient, Pearson correlation coefficient, and multivariate linear regression model (continuous variables), or Student's t-test (mean differences).

RESULTS

Both the HBeAg-negative CHB and HBeAg-positive CHB patient groups exhibited elevated serum levels of apoM. Moreover, serum apoM levels were positively correlated with serum HBV DNA levels in HBeAg-negative CHB patients (r = 0.394, p < 0.001). Conversely, there was no significant relationship between apoM and HBV DNA levels in the HBeAg-positive CHB group (r = 0.197, p = 0.170). The median log copies/mL value for HBV DNA (4.00) was considered the cutoff point for the HBeAg-negative CHB group. Notably, a significant number of patients with HBV DNA levels above the cutoff point also had higher serum apoM levels (63.38 ± 29.84 vs. 41.41 ± 21.84; p = 0.001).

CONCLUSIONS

Our findings reveal that the correlation between serum apoM levels and viral loads may depend on HBeAg status, as serum apoM levels were positively correlated with HBV DNA levels in HBeAg-negative CHB patients. These results suggest that HBeAg may play a role in apoM-related lipid metabolism and anti-inflammatory functions in hepatitis B patients. Thus, our findings may facilitate the clinical management of HBV infection.

Lipidomic Perturbations in Lung, Kidney, and Liver Tissues of p53 Knockout Mice Analyzed by Nanoflow UPLC-ESI-MS/MS

Lipids are important signaling molecules regulating biological processes under normal and diseased conditions. Although p53 mutation is well-known for causing cancer, the relationship between p53-related tumorigenesis and altered lipid profile is unclear. We profiled differences in lipid expressions in liver, lung, and kidney in p53 knockout (KO) mice by high-speed quantitative analysis of 320 lipids (399 species identified) using nanoflow ultrahigh performance liquid chromatography-tandem mass spectrometry (nUPLC-MS/MS). Lung tissues were most severely affected by the lack of p53 gene, as shown by significant reduction (24-44%, P < 0.05) in total phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), diacylglycerol (DG), and triacylglycerol (TG), and significant increases (30-50%) in phosphatidylserine (PS), phosphatidylinositol (PI), and monohexosylceramide (MHC). MHC levels increased in all tissues. Dihexosylceramide (DHC) level decreased only in kidney tissue. Most PI, PS, and phosphatidic acid (PA) species showing significant increases contained a saturated acyl chain (18:0) in lung and liver tissues. Neutral glycerolipids (16:0/22:0-DG and most TGs with saturated and monounsaturated acyl chains) decreased 2-4-fold in the liver tissue. Our results suggest that the lack of p53 and altered lipid profiles are closely related, but as their changes vary from one tissue to another, the lipid alterations are tissue-specific.

Lipoprotein (a): impact by ethnicity and environmental and medical conditions

Levels of lipoprotein (a) [Lp(a)], a complex between an LDL-like lipid moiety containing one copy of apoB, and apo(a), a plasminogen-derived carbohydrate-rich hydrophilic protein, are primarily genetically regulated. Although stable intra-individually, Lp(a) levels have a skewed distribution inter-individually and are strongly impacted by a size polymorphism of the LPA gene, resulting in a variable number of kringle IV (KIV) units, a key motif of apo(a). The variation in KIV units is a strong predictor of plasma Lp(a) levels resulting in stable plasma levels across the lifespan. Studies have demonstrated pronounced differences across ethnicities with regard to Lp(a) levels and some of this difference, but not all of it, can be explained by genetic variations across ethnic groups. Increasing evidence suggests that age, sex, and hormonal impact may have a modest modulatory influence on Lp(a) levels. Among clinical conditions, Lp(a) levels are reported to be affected by kidney and liver diseases.

Serum lipid profiling of patients with chronic hepatitis B, cirrhosis, and hepatocellular carcinoma by ultra fast LC/IT-TOF MS

In this study, an ultra fast LC/IT-TOF MS (UFLC/IT-TOF MS)-based serum lipidomics method was employed to characterize the serum lipid profile of patients with chronic hepatitis B, cirrhosis, and hepatocellular carcinoma (HCC). After data collection and processing, 96 lipids including lysophosphatidylcholines, phosphatidylcholines, sphingomyelins, triacylglycerides, and cholesterol esters were identified and used for subsequent data analysis. Partial least squares-discriminant analysis revealed that patients with liver diseases had distinctly different serum lipid profile from that of healthy controls; while cirrhosis and HCC patients had a similar serum lipid profile, but different from that of hepatitis patients. The ANOVA analysis found 75 of the 96 identified lipids to be abnormally regulated, among which most of these lipids were downregulated in cirrhosis and HCC patients compared with those of healthy controls and hepatitis patients, while hepatitis patients induced several lipids downregulated and others upregulated compared with those of healthy controls, indicating the aberrant lipid metabolism in patients with liver diseases. This work demonstrated the utility of UFLC/IT-TOF MS-based serum lipidomics as a powerful tool to investigate the lipid metabolism of liver diseases.

Lipoprotein(a) as a potential marker of residual liver function in hepatocellular carcinoma

The residual liver function is a major clinical index in hepatocellular carcinoma (HCC) patients. As the liver plays a crucial role in lipid and lipoprotein metabolism, the significant impairment of the hepatic function occurring during chronic liver diseases, such as HCC, can influence plasma lipoprotein profiles. Although, lipoprotein(a) (Lp(a)) circulating concentrations are mostly determined by genetic factors, in the majority of reports they have shown a correlation with the hepatic status and a significant decrease in HCC and liver cirrhosis patients than among the controls. In such a way, Lp(a) may represent a new additional and useful marker for a more complete assessment and monitoring of the liver function in patients with HCC and liver cirrhosis. Further studies are needed in order to evaluate the clinical significance of Lp(a) in HCC.

Enchanced levels of apolipoprotein M during HBV infection feedback suppresses HBV replication

Background

Chronic liver diseases can interfere with hepatic metabolism of lipoproteins, apolipoproteins. Hepatitis B virus (HBV) is a major etiological agent causing acute and chronic liver diseases. Apolipoprotein M (ApoM) is a high-density lipoprotein (HDL) apolipoprotein and exclusively expressed in the liver parenchyma cells and in the tubular cells of the kidney. This study was to determine the correlation between HBV infection and ApoM expression.

Materials and methods

Serum ApoM levels in patients with HBV infection and in healthy individuals were measured by ELISA, ApoM mRNA expression were determined by RT-PCR, and the expression of S and E proteins of HBV, as well as the synthesis of viral DNA were measured by ELISA and real-time PCR.

Results

The levels of serum ApoM was significantly elevated in patients as compared to healthy individuals (P < 0.001), ApoM promoter activity, mRNA and protein expression were all stimulated in cells transfected with infectious HBV clone. In addition, ApoM decreases the expression of S and E proteins of HBV and the synthesis of viral DNA.

Conclusion

Raised ApoM levels in HBV infection may in turn suppress HBV replication, one of the protective mechanisms of nature.

Expression of apolipoprotein M in human hepatocellular carcinoma tissues

The present study examined mRNA levels and protein mass of apolipoprotein M (apoM) in human hepatocellular carcinoma (HCC) tissues and in the adjacent tissues. Plasma apoM levels in these HCC patients were also determined and compared to the normal subjects. The mean level of plasma apoM in the HCC patients was 0.61±0.30ODmm⁻², which was significantly higher than that in the normal subjects 0.37±0.07ODmm⁻² (P<0.01). However, both apoM mRNA levels and apoM protein mass in the HCC tissues were significantly lower than in the adjacent tissues (P<0.05). It is concluded that human hepatocellular carcinoma tissues had a reduced capacity to produce apoM than the adjacent non-tumor tissues. However, the plasma apoM levels were higher in the HCC patients than in normal subjects, which suggested that tissues adjacent to the tumors or extra-hepatic apoM production in the HCC patients may contribute to the higher plasma apoM levels in these patients. The clinical significance of apoM in relation to HCC still needs further investigation.

Expression and localization of apolipoprotein M in human colorectal tissues

Background

It has been well documented that apolipoprotein M (apoM) is principally expressed in the liver and kidney. However we found that there was weak apoM expression in other tissues or organs too, which could not be ignored. In the present study, we therefore examined apoM expression in human colorectal tissues including cancer tissues, cancer adjacent normal tissues, polyp tissues and normal mucosa as well as inflammatory mucosa.

Methods

Tissue samples were collected from patients who underwent surgical resection or endoscopic examination. ApoM mRNA levels were determined by the real-time RT-PCR and apoM protein mass were examined by the immunohistochemistry.

Results

ApoM protein can be detected in all colorectal tissues. However, apoM protein mass were significantly lower in the cancer tissues than its matched adjacent normal tissues, polyp tissues, normal mucosa and inflammatory mucosa. In parallel, apoM mRNA levels in the colorectal cancer tissues (0.0536 ± 0.0131) were also significantly lower than those in their adjacent normal tissues (0.1907 ± 0.0563) (P = 0.033). Interestingly, apoM mRNA levels in colorectal cancer tissues were statistic significant higher in the patients with lymph node metastasis than the patients without lymph node metastasis (P = 0.008). Patients under Dukes' C and D stages had much higher apoM mRNA levels than patients under Dukes' A and B stages (P = 0.034).

Conclusion

It is concluded that apoM could also be expressed in human colorectal tissues besides liver and kidney. ApoM mRNA levels in the colorectal cancer tissues were significantly increased in the patients with lymph node metastasis. Whether increased apoM expression in the patients with lymph node metastasis being related to patients' prognosis and the physiopathological importance of apoM expression in colorectal tissues need further investigation.

Tissue-specific and ubiquitous expression patterns from alternative promoters of human genes

BACKGROUND

Transcriptome diversity provides the key to cellular identity. One important contribution to expression diversity is the use of alternative promoters, which creates mRNA isoforms by expanding the choice of transcription initiation sites of a gene. The proximity of the basal promoter to the transcription initiation site enables prediction of a promoter's location based on the gene annotations. We show that annotation of alternative promoters regulating expression of transcripts with distinct first exons enables a novel methodology to quantify expression levels and tissue specificity of mRNA isoforms.

PRINCIPAL FINDINGS

The use of distinct alternative first exons in 3,296 genes was examined using exon-microarray data from 11 human tissues. Comparing two transcripts from each gene we found that the activity of alternative promoters (i.e., P1 and P2) was not correlated through tissue specificity or level of expression. Furthermore neither P1 nor P2 conferred any bias for tissue-specific or ubiquitous expression. Genes associated with specific diseases produced transcripts whose limited expression patterns were consistent with the tissue affected in disease. Notably, genes that were historically designated as tissue-specific or housekeeping had alternative isoforms that showed differential expression. Furthermore, only a small number of alternative promoters showed expression exclusive to a single tissue indicating that "tissue preference" provides a better description of promoter activity than tissue specificity. When compared to gene expression data in public databases, as few as 22% of the genes had detailed information for more than one isoform, whereas the remainder collapsed the expression patterns from individual transcripts into one profile.

CONCLUSIONS

We describe a computational pipeline that uses microarray data to assess the level of expression and breadth of tissue profiles for transcripts with distinct first exons regulated by alternative promoters. We conclude that alternative promoters provide individualized regulation that is confirmed through expression levels, tissue preference and chromatin modifications. Although the selective use of alternative promoters often goes uncharacterized in gene expression analyses, transcripts produced in this manner make unique contributions to the cell that requires further exploration.

Hepatocellular Carcinoma: Tumorigenesis and Prediction Markers

Hepatocellular carcinoma (HCC) is one of the most common malignancies. Although many advances have been made in the clinical study of HCC, the prognosis remains poor. Despite the discoveries in cancer biology in respect with physiological and pathological factors in relation to prognosis, HCC remains still a fatal disease due to late diagnosis. For improving the outcomes of patients with HCC, it is important to identify the factors predisposing to patient death. In recent years, based on cellular and molecular biology techniques, many tumor markers related to invasion, metastasis, recurrence and survival have been explored. However, routine biomarkers for the prediction of HCC evolution and prognosis are available in small number and less specific. These reviews focus on the recent advances in HCC tumorigenesis, revealing those biomarkers with prognosis significance or can be used for early detection.